1. Field of the Invention
The present invention relates to a solid-state imaging device and manufacturing method for the same, and in particular to a technique for preventing color-mixing that occurs as a result of light which has passed through a color filter being incident on the wrong light receiving device.
2. Related Art
Solid-state imaging devices, which are essentially the heart of digital cameras that have become widely used in recent years, take color images by using color filters to separate incident light into its constituent colors. FIG. 1 is a cross-sectional view showing a structure of a solid-state imaging device according to conventional technology.
As shown in FIG. 1, a solid-state imaging device 11 includes a semiconductor substrate 1101 which has photoelectric converters 1102 formed therein. A planarizing layer 1103, a light shielding film 1104, a planarizing layer 1105, color filters 1106, a planarizing layer 1107 and condenser lenses 1108 are sequentially formed on the semiconductor substrate 1101 and the photoelectric converters 1102.
Apertures 1104a are provided in the light shielding film 1104 such that incident light can reach the photoelectric converters 1102. The color filters 1106 transmit only specific wavelengths of light as a result of including organic pigment microparticles. Each color filter 1106 transmits red, green or blue light per pixel (“Introduction to Solid-State Imaging Devices”, Ando and Komobuchi, Ed. Eizo Joho Media Gakkai, Nihon Riko Shuppankai, 1999, pp. 183-188).
However, given that the color filters 1106 pertaining to conventional technology have film thicknesses of from 1.5 μm to 2.0 μm, incident light may travel an oblique path depending on an angle of incidence and be incident on the wrong photoelectric converter 1102, whereby color-mixing occurs. In other words, light that passes through a given color filter is incident on a photoelectric converter that does not correspond to the given color filter, whereby an incorrect quantity of incident light is detected.
In regard to this problem, the film thicknesses of the color filters 1106 may be reduced. By reducing the film thicknesses of the color filters 1106, incident light will not travel an oblique path unless the angle of incidence is extremely large.
However, there is a limit to this miniaturization since the pigment particles which constitute the color filters 1106 have a particle diameter of 0.1 μm. For this reason, as the film thicknesses of the color filters 1106 are excessively reduced, the distribution of pigment particles ceases to be uniform, sensitivity reduction and color irregularities occurs, and the color filters become impractical for use.
A technique for forming a color filter directly on the light shielding layer has also been proposed (Japanese Patent Application Publication No. 7-43517). FIG. 2 is a cross-sectional view showing a structure of a solid-state imaging device according to this conventional technique.
In FIG. 2, a solid-state imaging device 12 includes CCDs 1201, photodiodes 1202, pigmentation layers (color filters) 1203 and a light shielding film layer 1204, with a planarizing resin layer 1205 on the CCDs and photodiodes. However, even with this structure it is not possible to prevent color-mixing since the color filters remain thick enough to allow oblique light.